Preparation of photomechanical printing-surfaces.



- 1% Drawing.

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JOHN GASKIN WOOD, 0F EDINBURGH, SCOTLAND.

PREPARATION OF PHOTOMECHANICAL PRINTING-SURFACES.

To all whom it may concern:

Be it known that 1, JOHN GAsxIN WOOD, a subject of the King of theUnited Kingdom of Great Britain and Ireland, and resident of,10 St.Bernards Row, Edinburgh, Scotland, photolitho artist, have inventedcertain new and useful Improvements in and Relating to the Preparationof Photomechanical Printing-Surfaces, of which the following is aspecification.

This invention relates to a process for the preparation ofphotomechanical printing surfaces, in which a grained or sand blastedplate or stone is used.

In accordance with this invention a zinc or aluminium plate or a stonehas the surface thereof suitably sand-blasted or grained and theprinting surface thus produced is then coated in the usual manner withany of the usual sensitizing solutions such for example as bichromate ofammonia, albumen and water, or bichromate and fish glue, such solutionbeing preferably applied exactly as in the production of a line print.The sensitizing solution is then allowed to dry and the plate or stoneis thereafter coated with a thin level coating of any suitable acidresisting transfer ink such for example as an etching ink,photo-transfer ink or other acid resisting medium, by means of aprinters composition roller. In thus coating the plate or stone thehollows or recesses of the grain aswell as the tops or raised parts willbe coated; that is to say the surface of the plate or stone will. becoated all over, and the coating applied by the roller to the tops orraised parts of the grain will be slightly thicker than that applied tothe hollows, owing to the fact that the tops receive a greater pressurefrom the roller and consequently receive more of the medium carried bythe roller. The picture may now be printed on to the hollows or recessesof the plate or stone from an ordinary continuous tone photographicnegative and, as the light passes through the more or less transparentportions of the negative-which correspond to the shadows of the picture,it

first acts on the hollows of the grain where the plate is more thinlycoated, thereafter acting through the different portions of the negativeof v'aryingdensities until all the details of the picture have beenprinted in the hollows of the'plate or stone, and the Specification ofLetters Patent.

Patented Sept. 28, 1915.

Application filed July 1', 1914. Serial No. 848,475.

tops of the grain are acted on only at those portions of the picturerepresenting the deepest shadows.

When all parts of the picture, with the exception of the pure highlights, have been printed on the plate or stone the latter is ready fordevelopingand this may be effected by immersing in water and thereafterWlplng away everything which has not been fixed by the action of thelight passing through the negative. The plate or stone may be thenslightly etched and is afterward gummed and otherwise treated as anordinary lithographic plate or stone. The hollows or recesses of theplate or stone are thus utilized to produce the grain of the pictureitself and the sand-blasting or graining may be fine, medium, coarse orvery coarse to suit the different classes of work.

Claims:

1. The process for the preparation of photo-mechanical printingsurfaces, which consists in coating a grained surface with a sensitizingmaterial and then with a transfer material, and thereafter exposing thesurface to the actinizing efiect of light corresponding to the pictureto be produced and developing.

2. The process for the preparation o photo-mechanical printing surfaces,which consists in treating a sand-blasted or grained surface of a plateor stone, first with a sensitizing material and then with a transfermedium applied to both-the hollows or recesses of the grain and the topsor raised parts thereof, but applying said coating more thickly to saidtops or raised parts 'than to the hollows, then actinizing thesensitized plate thus prepared, by a light transmitted through anegative, and then developing the plate thus exposed, substantially asdescribed.

3. The process for the preparation of photo-mechanical printingsurfaces, which upon the hollows, then printing by transmitted light,through an ordinary continuous tone photographic negative, onto thehollows or recesses of the pla'teor stone, and there. after developingthe surface thus prepared and actinized, substantially as described.

4. The process .for the preparation of photo-mechanical printingsurfaces, Which consists in coating a grained surface with a sensitizingmaterial and then with an acid resisting material, and thereafterexposing the surface to the actinizing effect of light corresponding tothe picture tobe produced and after developing, lasting'etching thesurface in usual manner.

5. The process for the preparation of photo-mechanical printingsurfaces, which consists in treating a sand-blasted or grained surfaceof a plate or stone, first with a sensitizing material and then with anacid-resisting medium applied to both the hollows or recesses of thegrain and the tops or raised parts thereof, but applying said coatingmore thickly to said tops or raised parts than to the hollows, thena'ctinizing the sensitized plate thus'prepared, by a light transmitted,through-a negative, and then developing the plate thus exposed, andfinally etching it in usual manner.

6. The process for the preparation of photo-mechanical printingsurfaces, which consists in treating a sandblasted or grained plate orstone, first with a coating of sensitized solution and then with acoating of acid-resisting transfer ink applied to the surface of theplate through the medium of pressure exerted upon the hollows or recesses of the grain, as well as upon the tops or raised parts thereof,and in a manner to develop a thicker coating upon the raised parts thanupon the hollows, then printing by transmitted light, throughan ordinaryJOHN GASKIN WOOD.

Witnesses:

JAMES YATE JOHNSON, ARTHUR WALKER RUssELL.

